As seen in the spread of the portable telephone and notebook computer, terminals owned by users are being downsized steadily, and research and development of the mobile communication network and its standardization activity are being promoted. Principal service in the mobile communication network is audio or video talking between two parties. Standardization activities of various elemental techniques in the mobile communication network such as communication and service control are being conducted in 3GPP (3rd Generation Partner Project) and 3GPP2 (3rd Generation Partner Project 2) (see, for example, 3GPP2 X. 0013-002-0, X. 0013-012-0 Draft version 0.17.0). One of these elemental techniques is communication quality control in two-party talking service. A communication quality control method discussed in the standardization activities is as follows: when establishing one service communication session between users, a user declares information of communication resources needed in the service to a server which controls the communication quality, and the communication quality management server makes a decision whether the resources can be acquired.